EXPERIMENTAL STUDY ON THE INFLUENCE OF COARSE AGGREGATE (PEBBLE) ON PROPERTIES OF SELF-COMPACTING CONCRETE

The requirements of a self compacting concrete for the coarse aggregate are different from those of an ordinary concrete，the main indicator to measure the performance of coarse aggregate is grain shape and gradation． Taking the shape index and particle gradation of coarse aggregate as the variables，ensuring other conditions being the same，a self-compacting concrete was prepared，whose slumps，expansion rate，T50 time，V type funnel flow time， 7 d and 28 d cube compressive strength were tested． Test results showed that self compacting concrete the working performance and strength of the self-compacting concrete could not be increased regularly with an increase in the shape index． Relatively effect on the working performance of the shape index was greater than the effect on strength; influence of particle gradation on strength was greater than the effect on the working performance; effects on 7 d compressive strength of shape index and particle gradation were greater than those on 28 d strength． Based on test condition and mix proportions，when the shape index was 0. 348，big pebble particle gradation in the proportion was 50%，the working performance and the mechanical properties of the self compacting concrete were the best．